Spatial Mixing and Non-local Markov chains

We consider spin systems with nearest-neighbor interactions on an $n$-vertex $d$-dimensional cube of the integer lattice graph $\mathbb{Z}^d$. We study the effects that exponential decay with distance of spin correlations, specifically the strong spatial mixing condition (SSM), has on the rate of convergence to equilibrium distribution of non-local Markov chains. We prove that SSM implies $O(\log n)$ mixing of a block dynamics whose steps can be implemented efficiently. We then develop a methodology, consisting of several new comparison inequalities concerning various block dynamics, that allow us to extend this result to other non-local dynamics. As a first application of our method we prove that, if SSM holds, then the relaxation time (i.e., the inverse spectral gap) of general block dynamics is $O(r)$, where $r$ is the number of blocks. A second application of our technology concerns the Swendsen-Wang dynamics for the ferromagnetic Ising and Potts models. We show that SSM implies an $O(1)$ bound for the relaxation time. As a by-product of this implication we observe that the relaxation time of the Swendsen-Wang dynamics in square boxes of $\mathbb{Z}^2$ is $O(1)$ throughout the subcritical regime of the $q$-state Potts model, for all $q \ge 2$. We also prove that for monotone spin systems SSM implies that the mixing time of systematic scan dynamics is $O(\log n (\log \log n)^2)$. Systematic scan dynamics are widely employed in practice but have proved hard to analyze. Our proofs use a variety of techniques for the analysis of Markov chains including coupling, functional analysis and linear algebra

“Un aporte a la integración Universidad y Sociedad”

La presente ponencia surge de diferentes investigaciones que se desarrollan en la UNPA- UARG, referidas a los alumnos mayores de 25 años sin estudios secundarios completos, que ingresan según el Art. 7mo de la Ley de Educación Superior. Algunos de los resultados arribados en las mismas, nos permiten sostener que la Universidad se convierte en un espacio de formación para los sujetos que, teniendo experiencia laboral en algún área específica, deciden formarse en la misma. A su vez, en el camino de la formación, emergen satisfactores a necesidades que van más allá de los objetivos que se plantea la Educación Superior y que nos permiten pensar, que dicha experiencia puede convertirse en valiosa para otros sujetos. En este sentido se considera que existen sendos grupos en la sociedad posible de ser incentivado a dar este salto cualitativo en sus aprendizaje, De esta manera, desde el espacio universitario podríamos contribuir con la construcción de una sociedad más justa y solidaria que favorezca la movilidad social, a través de la formación de ciudadanos con igualdad de oportunidades en nuestro caso, con igualdad de oportunidades educativas

Geminiviral protein Rep interferes in PCNA sumoylation

Rep is a multifunctional protein essential for replication of geminivirus that interferes with the sumoylation of a key protein in the DNA replication, PCNA (Proliferating Cell Nuclear Antigen). It is known that Rep is capable of interacting with a plethora of plant proteins, including PCNA. Despite the biological significance remains unknown, it’s thought that this interaction should play a key role for generating new copies of the virus genome. Therefore, in order to characterize this interaction, we study which lysines are sumoylated in tomato PCNA (SlPCNA). Considering conservation, location and presence of sumoylation domain criteria, we have identified some candidate lysines and studied how its mutation affects this protein sumoylation in Escherichia coli assays. Finally, we plan to confirm and characterize the Rep interference on SlPCNA sumoylation and determine if this interference occurs in planta.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Evaluation of PUF and QKD integration techniques as root of trust in communication systems

Quantum Cryptography could be the next key technology in terms of secure communication, but, as with every new technology, it presents problems that need to be solved in order to become a reality in daily life. This work discusses the integration of Physical Unclonable Functions (PUFs) as a solution for the authentication of the endpoints in quantum communication protocols. The use of PUF constructions would allow the authentication of devices without the need of relying on third parties, and support switched trustworthy quantum communication channels; two unseen features in Quantum Key Distribution (QKD) until now. We analyze in detail PUF integration within the BB84 protocol, as it is the foundation for all QKD protocols, and two proposals for an authentication scheme are made, depending on the connection characteristics of the communication endpoints and the distance between them. These proposals are then generalized for other types of QKD protocol. Moreover, different types of PUF are analyzed to conclude which ones are the most suitable for our purpose.La Criptografía Cuántica podría ser la próxima tecnología clave en relación a la seguridad de las comunicaciones pero, como toda nueva tecnología, presenta problemas que deben ser resueltos antes de llegar a ser una realidad en el día a día. Este trabajo discute la integración de Funciones Físicas No-Clonables (PUFs, por sus siglas en inglés) como solución a la autenticación de los extremos en un protocolo de comunicación cuántica. El uso de PUFs permitiría la autenticación de dispositivos sin necesidad de depender de terceros, además de abrir la posibilidad a la conmutación de canales de comunicación cuántica; dos características nunca vistas en la Distribución Cuántica de Claves (QKD, por sus siglas en inglés) hasta ahora. Se analiza en detalle la integración de PUFs en el protocolo BB84, ya que es la base de todos los protocolos de QKD, y se proponen dos esquemas de autenticación distintos, atendiendo a las características de los extremos de la comunicación y la distancia entre ellos. Después, estas propuestas se generalizan para el resto de protocolos de QKD. Además, se estudian distintos tipos de PUF con el objeto de encontrar la más adecuada para nuestro propósito.Universidad de Sevilla. Grado en Físic

Transcriptional regulation os phenylalaline biosynthesis and utilization

Conifer trees divert large quantities of carbon into the biosynthesis of phenylpropanoids, particularly to generate lignin, an important constituent of wood. Since phenylalanine is the precursor for phenylpropanoid biosynthesis, the precise regulation of phenylalanine synthesis and utilization should occur simultaneously. This crucial pathway is finely regulated primarily at the transcriptional level. Transcriptome analyses indicate that the transcription factors (TFs) preferentially expressed during wood formation in plants belong to the MYB and NAC families. Craven-Bartle et al. (2013) have shown in conifers that Myb8 is a candidate regulator of key genes in phenylalanine biosynthesis involved in the supply of the phenylpropane carbon skeleton necessary for lignin biosynthesis. This TF is able to bind AC elements present in the promoter regions of these genes to activate transcription. Constitutive overexpression of Myb8 in white spruce increased secondary-wall thickening and led to ectopic lignin deposition (Bomal et al. 2008). In Arabidopsis, the transcriptional network controlling secondary cell wall involves NAC-domain regulators operating upstream Myb transcription factors. Functional orthologues of members of this network described have been identified in poplar and eucalyptus, but in conifers functional evidence had only been obtained for MYBs. We have identified in the P. pinaster genome 37 genes encoding NAC proteins, which 3 NAC proteins could be potential candidates to be involved in vascular development (Pascual et al. 2015). The understanding of the transcriptional regulatory network associated to phenylpropanoids and lignin biosynthesis in conifers is crucial for future applications in tree improvement and sustainable forest management. This work is supported by the projects BIO2012-33797, BIO2015-69285-R and BIO-474 References: Bomal C, et al. (2008) Involvement of Pinus taeda MYB1 and MYB8 in phenylpropanoid metabolism and secondary cell wall biogenesis: a comparative in planta analysis. J Exp Bot. 59: 3925-3939. Craven-Bartle B, et al. (2013) A Myb transcription factor regulates genes of the phenylalanine pathway in maritime pine. Plant J, 74: 755-766. Pascual MB, et al. (2015) The NAC transcription factor family in maritime pine (Pinus pinaster): molecular regulation of two genes involved in stress responses. BMC Plant Biol, 15: 254.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Release of antioxidant peptides from the body wall proteins of the sea cucumber Isostichopus fuscus

Proteases from the tentacles of the sea cucumber Isostichopus fuscus were partially purified and used to produce antioxidant peptides from body wall proteins of this marine species. Three proteins (105, 68, and 39 kDa) were identified by SDS-PAGE in the proteolytic extract of the tentacles. Protein hydrolyzates were generated with gelatin and crude protein substrates from body wall, and peptidic fractions lower and higher than 3 kDa were obtained to evaluate their oxygen radical scavenging capacity (ORAC). The 3 kDa-fraction obtained from the crude protein hydrolyzate showed the highest ORAC value (0.92 ± 0.04 μmol Trolox equivalent/mg protein). This fraction was selected to purify peptides potentially responsible for the activity that might be used as ingredients for development of functional foods.A.C.H.-S thanks the National Council of Science and Technology (CONACYT, Mexico) for a graduate scholarship and the “Universidad Autónoma Metropolitana” for giving the marine organisms. B.H.-L. thanks the Ministry of Economy and Competitiveness (MINECO) and the Spanish National Research Council (CSIC) for her “Ramón y Cajal” postdoctoral contract.Peer Reviewe

Avances en la calidad de las respuestas a preguntas de probabilidad después de una actividad de aprendizaje con tecnología

En la presente comunicación, se describen y comparan las respuestas de estudiantes de secundaria (13-14 años) a tres preguntas de un cuestionario de probabilidad antes y después de haber tenido actividades de aprendizaje con apoyo de tecnología. Las preguntas analizadas se relacionan con las nociones de variable aleatoria, espacio muestral, frecuencias y distribución en sus formas más elementales. Se asume la hipótesis de que los recursos que proporciona la tecnología permiten que los estudiantes perciban que las unidades de análisis de la probabilidad son clases de experiencias y no experiencias aisladas. Con esta hipótesis se pueden explicar algunos de los avances que los estudiantes alcanzaron en las respuestas al post-test en relación con las dadas en el pre-test. Las actividades realizadas pueden proporcionar a los estudiantes referentes para los conceptos abstractos de probabilidad que estudiarán más adelante